1. Field of the Invention
The present invention relates to a pattern analysis-based motion vector compensation apparatus and method, and more particularly to an apparatus and method for compensating for estimated motion vectors by deciding whether blocks for motion estimation are a pattern image.
2. Description of the Related Art
The motion estimation between image frames is necessarily carried out in image processing such as the frame rate up-conversion (FRC) and the Interlaced-to-progressive conversion (IPC). The motion estimation is used to estimate motion vectors and compensate for motions, and, in general, the block matching algorithm (BMA) is used for the estimation.
The BMA compares two consecutive frames/fields matching one block with another, and estimates one motion vector per block. Here, the motion vector is estimated by use of the known motion estimation error values, for example, the sum of Absolute Difference (SAD) values. Further, the motion compensation process compensates for motions by use of the estimated motion vectors.
However, the conventional motion estimation based on the block-based estimation brings out inaccurate motion vectors from time to time. In particular, precise motion vectors are hardly estimated by use of the BMA only with respect to images of periodic pattern, that is, identical images periodically repeated as shown in FIG. 1A. The periodic pattern is a pattern repeating a certain image in certain intervals, such as stairs, zebra, lattice, and so on.
Thus, when motion compensation is applied to the images of the periodic pattern based on the motion vectors estimated by use of the BMA, the block artifact occurs in the frame/field image compression as shown in FIG. 1B. The block artifact refers to a boundary discontinuity among neighboring blocks, and causes visible and objectionable images together with lower image quality. Such block artifact is caused when the block-based motion compensation is applied by use of estimated motion vectors without considering compensation with neighboring blocks.